This invention relates to an improved turret arrangement for automatic continuous web rewinding machines which have a rotating turret mounted on a swinging frame or apron. In such rewinding machines, web from a large roll, sometimes referred to as a "parent roll", is automatically wound onto cores to form smaller rolls having a diameter suitable for use by a consumer.
As described in detail below, the presently preferred embodiment of this invention can be used to modify Series 150 continuous web rewinding machines manufactured by Paper Converting Machine Company, of Green Bay, Wisconsin, as described in U.S. Pat. No. 2,769,600 (Kwitek), and U.S. Pat. No. 3,179,348 (Nystrand). These automatic web rewinding machines have a turret mounted for rotation within an apron which is pivotably mounted to the frame of the machine. This turret includes six rotatable mandrels which extend parallel to one another, parallel to the axis of the turret. The web being rewound passes from the parent roll to a bedroll of the machine, and is wound from the bedroll onto a core which is placed on a mandrel located at a winding station adjacent to the bedroll. A new core with glue applied to the core is mounted on an adjacent mandrel that will next approach the winding station.
In this prior art device, as the winding of the core at the winding station nears completion, the turret begins to index or rotate in order to bring the new core into position to receive the web. The apron is caused to swing toward the bedroll so that the new core is brought into close proximity to the bedroll. The web is severed by a mechanism internal of the bedroll working in concert with a cut-off roll and the free end of the web is then transferred onto the glue on the new core. On a standard 150 Series continuous winder as manufactured by Paper Converting Machine Company, this transfer will typically take place between 15 and 18 degrees above the horizontal center line of the bedroll.
Immediately after the transfer of the web onto the new core has been completed, the turret swings away from the bedroll so that the roll being wound does not contact the bedroll surface as it moves to its point of closest approach to the bedroll. This swinging motion of the apron is brought about by a swing cam that turns at a constant velocity in concert with other components within the machine. The turret finishes indexing at a dwell position. During the dwell period, the finished roll is removed by a strip mechanism, and a fresh core is positioned on one of the empty mandrels of the turret. Typically, the turret will remain in the dwell period for approximately one-third of the total winding cycle.
Thus, this prior art rewinding machine resorted to the expediency of a swinging apron for the turret in order to achieve an acceptable winding geometry. Two competing requirements of an acceptable winding geometry are (1) that each mandrel must be brought into close proximity to the bedroll in order to achieve a reliable transfer of the free end of the web onto a glued core on the mandrel, and (2) that the mandrels must be spaced sufficiently far from the bedroll to prevent the winding roll from scuffing against the bedroll. However, this prior art approach requires considerable complexity to achieve this result. In particular, means such as the swing cam must be provided to cause the apron to swing with respect to the frame. Typically, a boost cylinder is used in order to facilitate the swinging action. Typically used boost cylinders can result in excessive wear on gear trains used to transmit power to the turret.
Furthermore, the vibration and backlash of the turret and turret drive assembly brought about by the swinging turret design can adversely affect performance of the rewinding machine. These problems are particularly acute when the rewinding machine is run at high cycle rates, in which case the rate of oscillation of the swinging turret must be increased.
There have been a number of attempts in the past to overcome the aforementioned disadvantages of the Series 150 automatic web rewinding machines. For example, the manufacturer of these machines has proposed modifications to the machines in which the mandrel turret is able to rotate but not to swing. A cam box is used to accomplish rotation and dwell of the turret, and the web is transferred to a new core substantially on the horizontal center line of the bedroll of these modified machines. However, due to the tangent line of the web over the bedroll to the outer perimeter of the finished roll and the possibility for interference between this web and the newly-glued core on the incoming mandrel, a moving deflector bar was found necessary to deflect the web at and during the critical point of transfer to prevent undesired contact between the web and the glued core on the incoming mandrel. Such a deflector bar, of course, increases the cost, complexity, and possibility for unreliability in a rewinding machine.
Other proposed modifications to the Series 150 continuous winders contemplated locking the swinging apron in place, and effecting transfer of the web onto a fresh core at four degrees above the center line of the bedroll. In this proposed modification, a standard, 5/16 inch clearance was provided at all times between the periphery of the bedroll and the outer periphery of the mandrels. This proposed modification suffered from the disadvantage that a deflector bar was required in the event a roll with a finished diameter of less than four inches was to be wound.